Three men were given mandatory life sentences for the murder of Katherine man Ray Niceforo, with 20-year old Zak Grieve copping a 20 year non-parole period, despite having pulled out of the murder at the last minute.

Christopher Malyschko, who bludgeoned Niceforo to death with a spanner, received a life sentence with 18 years non-parole - less than Grieve because Malyschko had faced death threats from the victim, allowing him two years grace through an "exceptional circumstances" clause.

Justice Dean Mildren recommended the NT Administrator Sally Thomas exercise the "prerogative of mercy" to see Grieve released sooner.

But Northern Territory Criminal Lawyers Association president Russel Goldflam says her chances of doing so are slim, and likely to be dictated by politics.

"Although it's the Administrator who makes the decision, in fact it's cabinet, it's the politicians, because the Administrator can only act on the advice of Government," Mr Goldflam told 105.7 Mornings.

"These people will be at the mercy of the political winds of the day, and that's precisely why we have courts - to be at arm's length from politicians, arm's length from Government, to make sentencing on the circumstances of the case and not on the political winds of the day."

He said nowhere else in Australia was there mandatory life sentencing for murder, yet all Northern Territory governments since self-governance have supported the idea.

"It reduces confidence in the justice system when sentences have to be imposed that are clearly unfair," he said.

"(Mandatory sentence laws) are made by people who aren't experts in this area, unlike Justice Mildren - our longest serving judge, a man who has sat on probably hundreds of trials.

"There is nobody in the Territory more qualified and more able to be charged with the very, very burdensome task of sentencing a serious offender than a Supreme Court judge."

NT Attorney General John Elferink stands by mandatory sentencing for murder with minmum non-parole periods, saying he expects politicians to be more in touch with community expectations than the courts.